The invention is in the art of skis and runners for snowmobiles and sleds. The skis are flexible plastic skis provided with handles for maintaining the fronts of the skis in upwardly curved configurations.
Conventional snowmobile skis are constructed of metal. Plastic liners have been secured to metal skis to reduce collection of snow and ice on the skis and prevent wear of the metal. Rigid loops or handles secured to the front ends of the skis extend upwardly and curved rearwardly to connection structures on the skis. The loops maintain the upward curvatures of the skis and are used as handles for moving the snowmobiles. Rigid loops absorb and transfer impact forces subjected to the curved front of the skis when the skis encounter bumps, moguls, trail ruts, and terrain obstacles, such as rocks and logs. Rigid loops of metal or plastic often sustain bending and structural damage including breaking when subjected to repeated and high impact forces. The damaged and broken loops must be replaced for continued use of the snowmobiles. Examples of U.S. patents related to snowmobile skis and loops are as follows.
W. T. Antcliff in U.S. Pat. No. 3,123,373 discloses a flexible ski sled having a flexible metal runner with an adjustable curved front section for varying the surface tension and contact area between the runner and the snow. The front section of the runner is maintained in a bowed or curved shape with a flexible cord or cable anchored to a post attached to the runner and connected to the tip of the runner. The cord or cable allows the front section of the runner to flex rearwardly to compensate for impact forces applied to the runner. The sled rider can also flex the runner in lateral and vertical directions for steering the sled.
J. W. Fitzpatrick in U.S. Pat. No. 4,595,211 discloses a snowmobile ski having a flat longitudinal member with an upwardly curved forward end. A steering bar or keel having right angle side edges is joined to the bottom member. A plastic flexible strip secured to the bottom of the member inhibits the build up of frozen snow and ice. The plastic strip is a flat flexible plastic body that is bent upwardly and rearwardly about the curved forward end of the ski. A strap attached to the front end of the strip and an anchor on the ski retains the curved position of the front end of the plastic strip.
K. W. Metheny in U.S. Pat. No. 5,145,201 discloses an ultra high molecular weight plastic snowmobile ski having an adjustable curved front section. A variable length turnbuckle pivotally connected to the front tip of the ski and lugs joined to the top of the ski adjusts and holds the front section of the ski in a concave curved configuration.
V. M. Simmons in U.S. Pat. No. 5,360,220 discloses a flexible and resilient plastic snowmobile ski that deforms to absorb impact forces. The ski has a loop attached to the bottom of the front of the ski. The loop curves upwardly and rearwardly to an attachment on the top of the ski rearwardly of the front of the ski to limit movement of the loop and flexing of the front curved portion of the ski. The attachment in one example of the ski is an upright bolt attached to the top of the ski and extended through a longitudinal slot in the rear portion of the loop.
D. D. Cormican in U.S. Pat. No. 6,086,101 discloses a flexible ultra high molecular weight plastic snowmobile ski having a gas pre-load shock absorber pivotally connected to the front of the ski body and pivotally connected to upright longitudinal flanges joined to the top of the body of the ski. The shock absorber has a gas filled barrel and a shock rod to absorb impact forces imported to the ski.
The invention is a flexible snowmobile ski and handle mounted on the ski operable to hold the front portion of the ski in a biased upwardly curved position and allow the front portion of the ski to have limited rearward flexing action to compensate for impact forces transmitted to the ski. The ski has a generally flat body joined to its upwardly curved front portion. A pair of laterally spaced upright flanges joined to the body extend longitudinally along the length of the body. The handle has a transverse cross head located between the flanges. The head has a transverse longitudinal slot accommodating a transverse cylindrical member or bolt mounted on the flanges. In one embodiment the bolt extends through transverse aligned holes in the flanges to allow the head and handle limited longitudinal lost motion determined by the longitudinal length of the slot. In an alternate embodiment the bolt extends through longitudinal elongated slots in the flanges to increase the amount of lost motion which is determined by the combined longitudinal lengths of the slot in the head and slots in the flanges. The lost motion connection between the handle and flanges of the ski reduces stress, twisting and bending forces on the handle, flanges and ski. Impact forces applied to the curved front portion of the ski are partly absorbed by the spring or flexing of the curved front portion of the ski. The result is that bending and breakage of the handle and flanges is mitigated.
A preferred embodiment of the combined ski and handle has an elongated one-piece ski of compression molded ultra high molecular weight (UHMW) polyethylene. The ski has a generally flat body, a forwardly tapered front section and a rear section joined to the body. A pair of laterally spaced longitudinal flanges are joined to the tops of the body and rear section of the ski. A longitudinal keel is joined to the middle of the bottom of the ski. The handle has a convex curved body having a forward end turned around the front tip front section of the ski and extended along the front of the keel. A pair of fasteners, such as nut and bolt assemblies, firmly secures and anchors the forward end of the handle body to the ski. The rear end of handle body is joined to a transverse head having a transverse longitudinal slot. The head has opposite ends engageable with inside walls of the flanges and a bottom surface located in surface engagement with a top surface of the body between the flanges. The flanges guide and limit the movement of the head to linear longitudinal movements. The surface engagement of the head with the top of the body inhibits longitudinal twisting of the handle. A cylindrical member, such as a bolt extended through the slot in the head, mounts the head on the flanges. The bolt extends through transverse aligned holes in the flanges to allow the head and handle limited longitudinal lost motion determined by the longitudinal length of the slot. In an alternate embodiment, the cylindrical member extends through longitudinal slots in the flanges aligned with the slot in the head to increase the amount of lost motion which is determined by the combined longitudinal lengths of the slot in the head and slots in the flanges. The head and cylindrical member associated with the slots provides longitudinal sliding lost motion to the handle when impact forces are subjected to the front portion of the ski. Part of these forces are absorbed by the spring or flexing of the curved front portion of the ski. The reduction of force and stress on the handle mitigates bending, twisting, and breaking of the handle and flanges of the ski.